preparation

Preheat oven to 350°F.

Whisk together flour, sugar, baking powder, and salt in a large bowl.

Whisk together eggs, oil, and vanilla in another bowl until combined, then stir oil mixture into flour mixture until combined well. (Dough will be crumbly.) Stir in walnuts and chocolate chips. Transfer mixture to a lightly floured surface and knead until a dough forms.

Quarter dough and firmly press each piece into a 10- by 2-inch log. Arrange logs 2 inches apart on an ungreased large baking sheet.

Bake in middle of oven until golden, about 30 minutes. Leave oven on.

Loosen logs from baking sheet with a metal spatula, then transfer to a cutting board and cool 5 minutes. Cut logs crosswise with a large heavy knife into 1/2-inch-wide slices and arrange on baking sheet, standing upright, 1/4 inch apart. Bake cookies in middle of oven until golden all over with firm centers, 10 to 12 minutes. Transfer to a rack to cool completely. (Cookies will crisp as they cool.)